Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4647253 | Discrete Mathematics | 2014 | 9 Pages |
Abstract
Let Î denote a bipartite distance-regular graph with diameter at least 4 and valency at least 3. Fix a vertex of Î and let T denote the corresponding Terwilliger algebra. Suppose that Î is Q-polynomial and there are two non-isomorphic irreducible T-modules with endpoint 2. We show that, unless the intersection numbers of Î fit one exceptional case (which is not known to correspond to an actual graph), the entry-wise product of pseudo primitive idempotents associated with these modules is a linear combination of two pseudo primitive idempotents. This result relates to a conjecture of MacLean and Terwilliger.
Related Topics
Physical Sciences and Engineering
Mathematics
Discrete Mathematics and Combinatorics
Authors
Michael S. Lang,